English Words Starting With R

• radiation belt

  nounC2
  /ˌreɪ.diˈeɪ.ʃən belt/A region of intense magnetically trapped charged particles, primarily electrons and protons, surrounding a planet, notably Earth.
• radiation fog

  nounC1/C2
  /ˌreɪ.diˈeɪ.ʃən fɒɡ/A common type of fog that forms overnight under clear skies when heat radiates from the Earth's surface into space, cooling the ground and the air directly above it to its dew point.
• radiation pattern

  nounC1/C2
  /ˌreɪ.diˈeɪ.ʃən ˈpæt.ən/The spatial distribution of electromagnetic radiation emitted from an antenna or other source.
• radiation potential

  nounC2 / Very Rare
  /ˌreɪ.diˈeɪ.ʃən pəˈten.ʃəl/A measure of an object's or substance's capacity to emit energy as electromagnetic waves or as moving subatomic particles.
• radiation pressure

  nounC2
  /ˌreɪ.diˈeɪ.ʃən ˈpreʃ.ər/The physical pressure exerted upon a surface by an electromagnetic wave or by photons.
• radiation pyrometer

  nounVery Low
  /ˌreɪ.diˈeɪ.ʃən paɪˈrɒm.ɪ.tə/A device that measures the temperature of a surface by detecting the intensity of the infrared radiation it emits, without physical contact.
• radiation resistance

  nounC1
  /ˌreɪ.diˈeɪ.ʃən rɪˈzɪs.təns/The property of a material or organism to withstand damage from exposure to radiation.
• radiation sickness

  nounLow in everyday language, high in medical and scientific contexts.
  /ˌreɪ.diˈeɪ.ʃən ˈsɪk.nəs/An illness resulting from exposure to ionizing radiation, characterized by symptoms such as nausea, vomiting, and fatigue.
• radiational cooling

  nounC2 / Very low frequency
  /ˌreɪ.diˈeɪ.ʃən.əl ˈkuː.lɪŋ/The process by which a surface, especially the Earth's surface, loses heat by radiating it out into space, typically at night under clear skies.
• radiative capture

  nounC2
  /ˌreɪ.di.eɪ.tɪv ˈkæp.tʃər/A nuclear reaction where an atomic nucleus absorbs a neutron or proton and subsequently emits gamma radiation to reach a stable state.
• radiator

  nounB1
  /ˈreɪ.di.eɪ.tə(r)/A device, typically a hollow metal panel with hot water or steam flowing through it, used to heat a room.
• radiator grille

  nounB2
  /ˈreɪ.di.eɪ.tə ɡrɪl/The visible, often decorative, perforated covering at the front of a vehicle designed to allow air to flow into the radiator and engine compartment for cooling.
• radical

  adjectivenounC1
  /ˈræd.ɪ.kəl/Relating to the fundamental, root, or source of something; complete and far-reaching change.
• radical axis

  nounLow
  /ˈræd.ɪ.kəl ˈæk.sɪs/In geometry, the line consisting of all points from which tangents drawn to two given circles have equal length.
• radical chic

  nounLow to Medium
  /ˌræd.ɪ.kəl ˈʃiːk/The fashionable affectation, typically by wealthy or celebrity figures, of supporting radical left-wing or revolutionary political causes, often superficially.
• radical empiricism

  nounC1/C2
  /ˌræd.ɪ.kəl ɪmˈpɪr.ɪ.sɪ.zəm/A philosophical doctrine, developed by William James, that experience is the fundamental source of all knowledge and concepts, rejecting the existence of any a priori truths or distinctions not grounded in experience.
• radical expression

  nounC2
  /ˌræd.ɪ.kəl ɪkˈspreʃ.ən/In mathematics, an algebraic expression containing a radical symbol (√), most commonly a square root, cube root, or higher-order root.
• radical left

  nounMedium
  /ˈræd.ɪ.kəl left/A term for individuals, groups, or political ideologies advocating for fundamental, revolutionary change in social, political, and economic structures, typically towards greater equality and against established hierarchies.
• radical right

  nounLow
  /ˈrædɪkəl raɪt/A political movement or ideology characterized by extreme conservative or reactionary views, often emphasizing nationalism, traditionalism, and opposition to social liberalism.
• radical sign

  nounLow (Specialist Technical)
  /ˌræd.ɪ.kəl ˈsaɪn/The symbol (√) placed before a number or quantity to indicate the extraction of a root, most commonly the square root.

Showing 201–220 of 5802 words.